Efficient content caching is essential to address the explosive growth of multimedia contents and most works on content cache placement have been proposed mainly based on the popularity of content. ...Since the priority of content is also an important attribute of content, we consider both popularity and priority of content together for content caching in information-centric networking (ICN). We define weighted delivery cost of content as content delivery cost multiplied by a weighted sum of popularity and priority of the content. Then, we formulate optimized content cache placement problem to minimize weighted content delivery cost for all content requests in a hierarchical network architecture with multi-access edge computing (MEC) and software-defined networking (SDN) controller. Average quality of experience (QoE), i.e., average content delivery cost, for contents with each priority is imposed as constraint. The number of content requests is predicted based on seq2seq long short-term memory (LSTM) model in MECs and this is delivered to SDN controller. Then, SDN controller obtains predicted popularity of contents and decides content placement in MECs and core routers by solving the content cache placement optimization problem based on binary particle swarm optimization (BPSO). Performance of the proposed content caching scheme is compared with conventional popularity-based, popularity prediction-based, and popularity prediction-based optimization schemes, from the aspect of QoE satisfaction ratio, average cost, weighted average cost, total cost, and weighted total cost. Numerical results show the effectiveness of the proposed scheme at caching content with high priority efficiently, at the expense of caching content with low priority.
In this article, we present a real-time 3D hybrid beamforming approach for 5G wireless networks. One of the key concepts in 5G cellular systems is the small cell network, which settles the high ...mobile traffic demand and provides uniform user-experienced data rates. The overall capacity of the small cell network can be enhanced with the enabling technology of 3D hybrid beamforming. This study validates the feasibility of 3D hybrid beamforming, mostly for link-level performance, through the implementation of a real-time testbed using a SDR platform and fabricated antenna array. Based on the measured data, we also investigate system-level performance to verify the gain of the proposed smart small cell system over LTE systems by performing system-level simulations based on a 3D ray-tracing tool.
Reducing energy consumption of mobile communication networks has gained significant attentions since it takes a major part of the total energy consumption of information and communication technology ...(ICT). In this paper, we consider 5G networks with heterogeneous macro cells and small cells, where data and control planes are separated. We consider two types of data traffic, i.e., low rate data traffic and high rate data traffic. In basic separation architecture, a macro cell base station (MBS) manages control signals, while a small cell base station (SBS) manages both low rate data traffic and high rate data traffic. In the considered modified separation architecture, an MBS manages control signals and low rate data traffic, while an SBS manages high rate data traffic. Then, an efficient energy saving scheme for base stations (BSs) is proposed, where the state of a BS is determined depending on the number of user equipments (UEs) that request high rate data traffic and the number of UEs that exist under the overlapping areas commonly covered by the considered BS and the neighbor BSs. We formulate an optimization problem for the proposed energy saving scheme and obtain the solution using particle swarm optimization (PSO). Numerical results show that the proposed energy saving scheme in the modified separated network architecture has better energy efficiency compared to the conventional energy saving schemes in both basic and modified separated network architectures. Also, the proposed energy saving scheme has lower aggregate delay.
Enchondroma is the most common bone tumor in the hand. While standard surgical procedure is intra-lesional excision and bone grafting, there is a dispute between allogeneic bone, autogenous bone, and ...synthetic bone substitute grafting. Diverse adjuvant treatments have been introduced to reduce recurrence, but results are mixed with controversies. Meanwhile, whether existing descriptive classification could predict treatment outcome remains unclear. Thus, we reviewed patients with solitary enchondroma of the hand who underwent simple curettage followed by allogeneic cancellous bone chip impaction grafting. Eighty-eight patients with more than 5 years of follow-up were enrolled. Demographic data, local recurrence, and complications were reviewed. Duration of consolidation and the difference according to Takigawa classification were assessed. Range of motion (ROM), and functional scores were also evaluated. There were 51 women and 37 men, with a mean age of 37.9 years. Mean follow-up was 10.2 years. Recurrence occurred only in one patient. There was no complication. Mean postoperative total active motions of fingers and thumb were 239° and 132.9°. Mean modified Disabilities of the Arm, Shoulder, Hand score, and Musculoskeletal Tumor Society Score were 1.63, and 99.2 at the last follow-up. Consolidation, ROM, and functional scores according to Takigawa classification showed no significant differences. This study suggests that simple curettage with impaction grafting of allogeneic cancellous bone chip is a feasible method for treating solitary enchondromas involving short tubular bone of the hand with good long-term outcomes. Postoperative recurrence and complication rates were very low. Radiographic and clinical results were good regardless of the previous radiological classification.
The oncologic risk of ionizing radiation is widely known. Sarcomas developing after radiotherapy have been reported, and they are a growing problem because rapid advancements in cancer management and ...screening have increased the number of long-term survivors. Although many patients have undergone radiation treatment in Asian countries, scarce reports on post-radiation sarcomas (PRSs) have been published. We investigated the feature and prognostic factors of PRSs in an Asian population. The Eastern Asian Musculoskeletal Oncology Group participated in this project. Cases obtained from 10 centers were retrospectively reviewed. Patients with genetic malignancy predisposition syndrome, or who had more than one type of malignancy before the development of secondary sarcoma were excluded. Forty-two high-grade sarcomas among a total of 43 PRSs were analyzed. There were 29 females and 13 males, with a median age of 58.5 years; 23 patients had bone tumors and 19 had soft tissue tumors. The most common primary lesion was breast cancer. The median latency period was 192 months. There were no differences in radiation dose, latency time, and survival rates between bone and soft tissue PRSs. The most common site and diagnosis were the pelvic area and osteosarcoma and malignant fibrous histiocytoma for bone and soft tissue PRSs. The median follow-up period was 25.5 months. Five-year metastasis-free and overall survival rates were 14.5% and 16.6%, and 39.1% and 49.6% for bone and soft tissue PRSs. Survival differences depending on initial metastasis and surgery were significant in soft tissue sarcomas. Although this study failed to find ethnic differences, it is the largest review on PRS in an Asian population. As early recognition through long-term surveillance is a key to optimal management, clinicians should take efforts to understand the real status of PRS.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Wearable Electronics
In article number 2200256, Seungjun Chung, Chong Rae Park, Heesuk Kim and co‐workers fabricate a highly integrated, wearable carbon‐nanotube‐yarn (CNTY)‐based thermoelectric ...generator (TEG) by precisely doping CNTY into p‐ and n‐type segments via picoliter scale inkjet printing (depicted as splash of solution). The TEG can conformably wrap around bodies and harvest electric energy directly from body heat.
Iron‐nitrogen‐carbon (Fe−N−C) catalysts are one of the most promising family of materials for the successful replacement of noble Pt in low‐temperature fuel cells. Despite recent advances in the ...synthesis, activity, and site‐structure of Fe−N−C catalysts, further improved understanding of the nature of the Fe‐based active sites is still needed. In the present study, the existence of two sub‐families of FeNxCy moieties is revealed by the concentration dependence of cyanide poisoning on a Fe−N−C catalyst only comprising of atomically dispersed iron. The analysis of the activity decrease upon contact with various cyanide concentrations and activity recovery following rinsing with water reveals the presence of two sub‐groups of ORR‐active FeNxCy species. They are discriminated by the reversibility or irreversibility of the cyanide poisoning. From a Mössbauer spectroscopy study and poisoning test on a model compound, Fe(II) phthalocyanine (FePc), we hypothesize that the reversibility/irreversibility of cyanide poisoning is governed by the competitive adsorption of oxygen molecule and cyanide anion. It is proposed that FeNxCy moieties with Fe in low spin state reversibly adsorb cyanide, whereas those with a medium spin state irreversibly adsorb cyanide.
The presence of multiple FeNxCy species in Fe−N−C catalysts is studied with various concentrations of cyanide ions under conditions of the electrochemical oxygen reduction reaction, allowing two (or more) different types of atomic Fe sites to be observed, which are reversible or irreversible to the cyanide poisoning (see picture).
A novel synthesis of N-doped carbon with not only a high surface area (∼1000m2g−1) but also with a controlled amount of N-doping is reported from the solvothermal reduction of hexachlorobenzene (HCB) ...and pentachloropyridine (PCP), without the emission of harmful byproducts. In the presence of metallic sodium as a reducing agent, the N-doping amount can be regulated up to 0.12 of N/C atomic ratio by simply altering the initial HCB and PCP ratios. The mechanism is proposed where the chlorine in the HCB and PCP is reacted with metallic sodium by producing NaCl, and the N-doped carbon is synthesized as the activated carbon edges of C5N and C6 rings being bonded together. The surfaces of the prepared N-doped carbons are modified through heat-treatment and this dramatically improves the mechanical and electrical properties. The dominant doping phases of N are pyridinic-N and amide or amine groups; however, the amide or amine groups are eliminated and graphitic-N is newly generated through heat-treatment.
In bone sarcomas, chemotherapy has improved the prognosis with advances in diagnostic and surgical technologies, which has led to attempts to save limbs. As early detection and multidisciplinary ...treatment have improved the survival rate, curative surgery is considered for selected patients with metastatic bone carcinomas. Limb salvage procedures may vary in relation to the reconstruction method, which is accompanied by different complications. To overcome them, we devised a novel concept,
local tumor ablation and recycling machine based on radiofrequency (RF)-induced heating and intended experiments to demonstrate its feasibility.
The fresh femurs of 6-month-old pigs were used after removing the epiphyses; the distal parts were placed in a heating chamber. Fiber-optic temperature sensors were inserted in the metaphysis, meta-diaphysis, and diaphysis. Temperatures were measured six times each during heating at 27.12 MHz at various powers. Additionally, the compressive and bending stiffnesses were measured six times each for the unprocessed, RF-treated, and pasteurized bones, and the results were compared.
Under 200 W power output, the temperatures at all measurement sites reached 70 ℃ or higher in 6 minutes, and the temperatures were maintained. The median compressive stiffness of RF-heated bones was 79.2% higher than that of pasteurized bones, but the difference was statistically insignificant. The median bending stiffness of RF-heated bones was approximately 66.3% of that of unprocessed bones, which was 20% higher than that of pasteurized bones.
The feasibility to rapidly attain and maintain temperatures for tumor ablation is shown, which favorably preserves bone stiffness through the
local tumor ablation and recycling based on RF heating. The problem of nonuniform temperature distribution might be solved by an optimal design determined from simulation research and additional experiments.
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